This invention relates to absorbent articles particularly absorbent structures that are useful in personal care products such as disposable diapers, incontinence guards, and childcare training pants and the like. More particularly, the invention relates to absorbent articles that have a portion designed for the release of volumes of vapor upon the insult of the article, thus driving moisture out of the article, reducing the humidity and, as a result, the detrimental effect on the skin of bodily exudates.
Personal care products are absorbent articles including diapers, training pants, incontinence devices and the like. These products are designed to absorb and contain body exudates and are generally single-use or disposable items which are discarded after a relatively short period of usexe2x80x94usually a period of hoursxe2x80x94and are not intended to be washed and reused. Such products are placed against or in proximity to the wearer""s body to absorb and contain various exudates discharged from the body. All of these products typically include a liquid permeable bodyside liner or cover, a liquid impermeable outer cover or backsheet, and an absorbent structure disposed between the bodyside liner and outer cover. The liquid impermeable outer cover may be breathable, i.e., permeable to water vapor.
It has been found that urination can occur at rates as high as 15 to 20 milliliters per second and at velocities as high as 280 centimeters per second. The volume of urine released per occurrence can vary from about a nominal amount to about 100 ml. It""s important for the absorbent article to rapidly uptake liquid to avoid excessive pooling of liquid on the body-facing surface of the bodyside liner in order to avoid leakage. Even if absorbed, however, any liquid in the article contributes to the overall humidity near the wearer skin, causing discomfort and potential skin health problems.
The problem of excessive humidity near the skin in an absorbent article has been addressed in the art through a number of means. U.S. Pat. No. 5,137,525 for example, uses mechanical means to increase airflow in the article. Breathable outer covers allow air and water vapor diffusion and have been mentioned previously.
Despite these attempts, the need exists for further improvement in the reduction of humidity within absorbent articles. In particular, there is a need for materials that can flush or sweep excess humidity from the article. Ideally, this sweeping or flushing should occur after or in response to insult and not on a continuous basis. The present invention provides for such improved moisture reduction within an absorbent article.
The objects of this invention are achieved by a personal care product having a vapor sweep comprising a material that reacts with water or urine to form vapor at a rate capable of displacing at least 5 percent, and preferably at least 10 percent, of the air volume within said product per minute. This vapor generation sweeps water vapor and humidity from the personal care product, such as a diaper, and so it""s believed will contribute to skin health. Materials that, upon reaction with water or urine, produce large volumes of a nontoxic gas such as carbon dioxide may be incorporated into the various components of standard personal care products to achieve the objective of this invention. Such materials include leavening agents. Additionally, a seal may be added to the personal care product to encourage the generated vapor to travel a longer path prior to exiting the product in order to maximize water vapor removal.